A Comprehensive Review of User Authentication and Authorization Techniques in Cloud Computing
Cloud computing has emerged as a transformative paradigm for delivering scalable, flexible, and cost-effective computing services over the Internet. As organizations increasingly rely on cloud platforms for data storage, application hosting, and resource management, ensuring secure access to cloud resources has become a critical challenge. Authentication and authorization mechanisms play a fundamental role in protecting cloud environments by verifying user identities and regulating access privileges. This paper presents a comprehensive review of user authentication and authorization techniques in cloud computing. The study examines widely adopted authentication approaches, including password-based, multi-factor, biometric, and behavioral authentication methods, as well as authorization models such as Role-Based Access Control (RBAC), Attribute-Based Access Control (ABAC), and Mandatory Access Control (MAC). Furthermore, recent advancements in artificial intelligence-driven authentication, fine-grained access control, graphical authentication systems, and cloud security frameworks are reviewed and analyzed. The findings indicate a significant transition from traditional security mechanisms toward intelligent, adaptive, and context-aware solutions that enhance security, usability, and access management. The review highlights that multi-factor authentication, biometric technologies, behavioral analytics, and attribute-based authorization frameworks offer improved protection against evolving cyber threats and represent promising directions for securing modern cloud computing environments.